The invention generally relates to the field of a sliding window assemblies for use in the automotive industry. In particular, the invention concerns a sliding window assembly for positioning a window substantially flush with the exterior surface of a motor vehicle.
As performance efficiency has become more and more important with motor vehicles, considerable attention has been focused on improving the aerodynamic features of the vehicle body. Studies have shown that a substantial amount of the resistance, or drag, on a moving vehicle is due to the vehicle windows being recessed in the sides of the vehicle body. These recesses in the otherwise smooth surface of the vehicle body create circular air currents, or eddies, which degrade the aerodynamic properties of the vehicle.
Additionally, consumer preferences indicate that it is aesthetically desirable for windows to be flush with the exterior surfaces of motor vehicles. Moreover, consumers also prefer flush windows because they eliminate wind noise inside the vehicle such as are caused by the above-described air currents.
Accordingly, there have been attempts to improve automobile aerodynamics and aesthetics by mounting vehicle windows more or less flush with the exterior surface of the vehicle body. While this is relatively simple to do in the case of fixed windows, it is difficult to achieve in the case of sliding windows. Some progress has been made in this area, however, by properly contouring the guides or tracks in which a window slides so that as the window is raised, it moves outwardly toward the exterior surface of the vehicle body. Such a system is disclosed in U.S. Pat. No. 4,561,211. Other window-door assemblies such as those disclosed in U.S. Pat. Nos. 4,454,688, 4,567,691, and 4,628,637 provide a somewhat flush mounted window by offsetting the window pane outwardly with respect to the track in which the window travels.
Another type of assembly includes a carriage which carries the window assembly and is supported by a linkage such that the carriage is shiftable. Such a system is described in U.S. Pat. No. 4,730,414 to Nakamora et al. and U.S. Pat. No. 4,771,575 to Tiesler. In both of these assemblies, vertically applied forces act on the linkage to cause a shifting of the window carrying carriage.
None of the known assemblies, however, has provided a completely satisfactory approach to providing a sliding window assembly which positions the window flush on all four sides with respect to the outer surface of the motor vehicle. While somewhat effective in various aspects, the known systems have been unable to achieve a completely flush window. Tests have shown, however, that even a relatively small amount of setback along an edge margin of the closed window can create appreciable drag and considerable wind noise inside a motor vehicle.
It is an object of the invention, therefore, to provide a sliding window assembly which positions the closed window completely flush with the motor vehicle body on all four sides of the window.